This happens if you did not define you own phrases inside the wp-config.php file. If the default is still in place at any of those defines like define(’AUTH_KEY’, ‘put your unique phrase here’); the internal validation fails. The failure reason is the additional file needed for russian language named “ru_RU.php” in cooperation with your wp-config.php file. Inside this file the default phrase has been changed to
PHP

$wp_default_secret_key = 'впишите сюда уникальную фразу';

instead of original ‘put your unique phrase here’. This can be solved if you modify the wp-config.php file with your own phases as highly recommended by WP core teams too.

So I've checked the file and there's any ru_RU.php but one for tr_TR and I realised what to do.

The downloadable version at ru.wordpress.org doesn't contain this ru_RU.php anymore.
The downloadable version at tr.wordpress.org contains a tr_TR.php file but it doesn't raise any issues with my plugin in version 1.3.11